Rogues
There probably the most dangerous you will face. Fear will always be your greatest weapon. Dont stand around to long. Their DPS is higher than yours so you wont last long. Fear when you need a break or to cast long spells, there all attack so if you keep them away from you you'll do fine.

Warriors
If you get Charged(stunned) at the beginning of battle, Use Seduction on them right away, you'll recover fast than he will and give you the opportunity to cast your spells to equal out any damage taken. Fear and Suduction will keep you alive. They dont have the greatest DPS but when they hit you'll feel it. Again if you get feared or stunned, use seduction to counter and keep the damage to you minimal.

Paladins
Like all melee attackers, Fear and Sudection will keep you alive. If you can keep them feared when your stunned you'll win 95% of the time. About halfway through the battle cast curse of tongues. This will slow down the casting time to their healing spell giving you that few extra seconds to cast a longer more powerful spell like Soulfire or a few shadow bolts.

Shamans
To me probably one of your hardest fight. If you come across an 'Elemental Shaman' your in for a fight. Earth shock will interupt spell casting, so its important to get out your instant spells quick. Keep moving, if you see a totem back off. Fear then Soulfire to do a huge amount of damage. When the shaman comes off his fear, seduction him and blast him with shadowbolts. Try and stay away from firespells if you see totems.

Hunters
Ignore the pet, and get in pretty close. Their DPS isnt as high as the others so youll last a little longer here. Get in close and cast howl of terror. Then start spamming the spells. Get your soulfire out about mid fight to drop his health down to nothing. This in an overall sense an easy fight if you keep him moving and the pet off of you.

Druids
Druids fall pretty easy if you keep your distance, just out of melee range. There health isnt as high as the other melee fighters, but their DPS is high enough if your not carefull youll die quick. Just attack them like a melee attacker and theyll fall. If they go into their humanoid form cast curse of tongues and continue casting bolts and searing pain.

Mages
This will be your toughest battle. Cast your spells and try and keep your health up. If you get counterspelled. Seduction or sacrifice your voidwalker to give you time till the effect wears off. Keep them feared as much as possible. Curse of tongues should be used when your Agony spell is about to wear off. This will help lessen the damage to you. Since most mages are arcane, they'll eat through mana quickly so if you do die rez asap and continue the fight. Most mages after a tough pvp fight need at least 30seconds to restore half of there mana which is more than enough to kill you again. Dont give them that chance. Keep your distance! Arcane Explosion is a killer and they can cast 2-3 before you can get out of range.

Preists
Most priests ive come across are shadow priests, and are pushovers to me cause I have a ton of shadow protection/resistance. If you dont. Cast curse of tongues and keep it on him, use your other non curse spells to kill him, most priests have relativley low HP, so use that to your advantage. If he starts to mana drain you, do it back to him! This will keep the mana points equal and will make it come down to who has the most health and who can cause the most DoT, which is you. Just keep your mana up!

Warlocks
Like fighting your twin. What ever you do he can do you back. You just have to have more hp and maximize your spell casting. This will be a back and forth battle. I rarely come across antoher warlock who wants to fight, cause he knows the battle is equal, and if your a warlock you should have high resistance to shadow, which is the bulk of most of your best DoT spells. So in good faith, most warlocks i come across we just pass each other. If you do get in a battle, start out the battle and keep your shadow ward spell up at all times. Fire spells will do the most damage in this fight, Curse of tongues is a helper but I would rather use Curse of agony over tongues in this fight.

Mind you, in most battles you should be able to hit Shadow Trance at least 2-3 times so spam out bolts when you see your trance state.